Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., from Old French comunion "community, communion" (12c.), from Latin communionem (nominative communio) "fellowship, mutual participation, a sharing," used in Late Latin ecclesiastical language for "participation in the sacrament," from communis (see common (adj.)). Used by Augustine, in belief that the word was derived from com- "with, together" + unus "oneness, union."
A sacrament of Christianity. In a reenactment of the Last Supper, the words of Jesus — “This is my body” and “This is my blood” — are spoken over bread and wine (the elements of Communion), which are then shared by the worshipers. Communion, also known as the Eucharist, commemorates the death of Jesus. (See transubstantiation.)
fellowship with God (Gen. 18:17-33; Ex. 33:9-11; Num. 12:7, 8), between Christ and his people (John 14:23), by the Spirit (2 Cor. 13:14; Phil. 2:1), of believers with one another (Eph. 4:1-6). The Lord's Supper is so called (1 Cor. 10:16, 17), because in it there is fellowship between Christ and his disciples, and of the disciples with one another.